DIN ISO 76 Beiblatt 2:2011

Rolling bearings - Static load ratings - Supplement 2: Load ratings for hybrid bearings

This supplement gives guidelines for the calculation of the static load rating for hybrid bearings. It is applicable for hybrid bearings with rings, manufactured from contemporary, commonly used, high quality hardened bearing steel, in accordance with good manufacturing practice and with rolling elements made of ceramic, commonly silicon nitride (Si<(Index)3>N<(Index)4>), with today's commonly used material- and manufacturing quality. When using hybrid bearings the reduced static load ratings and the recommendations for the static safety factor according to DIN ISO 76 have to be consider in comparison to conventional rolling bearings.*This supplement has been prepared by the Rolling Bearings and Plain Bearings Standards Committee (NAWGL), Working Committee NA 118-01-08 AA "Tragzahlen und Lebensdauer" ("Load ratings and life"). Hybrid bearings are rolling bearings with raceways consisting of commonly used rolling bearing steel and rolling elements consisting of ceramic, usually silicon nitride. Due to the higher modulus of elasticity of the ceramic rolling elements, hybrid bearings have a noticeably smaller contact ellipse at the same rolling element load than rolling bearings with rolling elements of steel. This will lead to higher contact stresses at the same load and therefore to a reduced static load-carrying ability. This supplement applies for hybrid bearings with bearing rings made of contemporary, commonly used, high quality hardened bearing steel in accordance with good manufacturing practice and rolling elements made of ceramic, usually silicon nitride (Si<(Index)3>N<(Index)4>) in contemporary, commonly used material and manufacturing quality. It contains no standardized provisions, but describes a method for the calculation of the dynamic load rating of hybrid bearings. When using hybrid bearings the reduced static load ratings and the recommendations for the static safety factor according to DIN ISO 76 in comparison to conventional rolling bearings shall be observed.